Multiplex harmony generator

ABSTRACT

A harmony generator provides signals for causing the output system of an electronic musical instrument to simultaneously sound a plurality of tones forming a chord, such tones corresponding to keys depressed on the left-hand or accompaniment keyboard of the instrument. The tones sounded by operation of the harmony generator are related in pitch to a key depressed by the operator on the righthand or solo keyboard of the instrument, to harmonize therewith. The harmony generator incorporates a matrix which is connected with switches individually actuated by operation of the keys of the two keyboards, and with decoders for identifying particular notes and octaves thereof, whereby the matrix produces a train of pulses representative of a plurality of individual keys, which is received by a logic unit and employed to store, in a plurality of latch units, representations of certain operated ones of the keys of the accompaniment keyboard, and certain data relating to the operated key of the solo keyboard which corresponds to the highest pitch. The latches develop output signals which are effective to select certain ones of a plurality of output signals of a tone signal generator and to selectively reduce them in frequency by an amount corresponding to the data stored in the latches, and then to cause each signal there produced to be connected through an individual voicing circuit prior to being connected with the output system of the instrument. The individual voicing of the tones sounded by the output system simulate an orchestration in which the various parts of a multi-part harmony are played by several separate instruments.

United States Patent [451 Dec. 30, 1975 Moore MULTIPLEX HARMONY GENERATOR [75] Inventor: Douglas R. Moore, Niles, Ill.

[73] Assignee: Chicago Musical Instrument Co.,

Lincolnwood, Ill.

[22] Filed: Oct. 23, 1973 [21] Appl. No.: 409,009

[52] US. Cl. .1 84/l.l7; 84/l.0l; 84/l.03

[|] Int. Cl. Gl0l-I 1/00; GlOH 3/06 [58] Field of Search 8411.01, 1.03, L17, 1.24, 84/DlG. 22

[56] References Cited UNITED STATES PATENTS 3,548,066 l2/l970 Freeman 84Il.l7 X

3,6l0,799 l0/l97l Watson 84/L0l 3,697,66l l0/l972 Deutsch... 84/l.0l

3,708,602 l/l973 Hiyama 84/l.l7

3,746,773 7/l973 Uetrecht 84/l.l7 X

3,752,898 8/l973 Obayashi 84/].01

3,842,l84 l0/l974 Kniepkamp et 34mm x Primary Examiner-L. T. Hix

Assistant Examiner-U. Weldon Attorney, Agent, or FirmHill, Gross, Simpson, Van Santen, Steadman, Chiara & Simpson 57 1 ABSTRACT A harmony generator provides signals for causing the output system of an electronic musical instrument to simultaneously sound a plurality of tones forming a chord, such tones corresponding to keys depressed on the left-hand or accompaniment keyboard of the instrument. The tones sounded by operation of the harmony generator are related in pitch to a key depressed by the operator on the righthand or solo keyboard of the instrument, to harmonize therewith. The harmony generator incorporates a matrix which is connected with switches individually actuated by operation of the keys of the two keyboards, and with decoders for identifying particular notes and octaves thereof, whereby the matrix produces a train of pulses representative of a plurality of individual keys, which is received by a logic unit and employed to store, in a plurality of latch units, representations of certain operated ones of the keys of the accompaniment keyboard, and certain data relating to the operated key of the solo keyboard which corresponds to the highest pitch. The latches develop output signals which are effective to select certain ones of a plurality of output signals of a tone signal generator and to selectively reduce them in frequency by an amount corresponding to the data stored in the latches, and then to cause each signal there produced to be connected through an individual voicing circuit prior to being connected with the output system of the instrument. The individual voicing of the tones sounded by the output system simulate an orchestration in which the various parts of a multi-part harmony are played by several separate instruments.

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U.S. Patent Dec. 30, 1975 Sheet 8 of8 3,929,051

mm U MULTIPLEX HARMONY GENERATOR BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to an electronic musical instrument and more particularly to an electronic musical instrument having means for automatically harmonizing tones in a predetermined relationship with one or more tones generated in response to depression of the keys of a keyboard of such instrument.

2. The Prior Art Various systems have been developed in the past for generating a series of fill-in tones simultaneously in response to operation of a number of keys of a keyboard. Typically, such systeins require the provision of multiple switches or multiple poles of a single switch simultaneously operative to close multiple conductive circuits and sometimes to open others, in response to depression of various keys of the keyboard. Depression of such keys changes the condition of all of the switches, or all of the poles of a single switch, associated with the operated key, to open and close a variety of electrical circuits. While such systems have operated satisfactorily, they are relatively complex and expen sive in construction, and they are operable in only a relatively limited manner which is not always the manner desired by the operator-player.

Moreover, in the previously known systems, the various tones were typically sounded either in the same voice as the tones normally selected, or in a plurality of voices selected in accordance with the degree of separation, in terms of the chromatic musical scale, between the pitches of the various tones which are sounded.

SUMMARY OF THE INVENTION One illustrative embodiment of the present invention comprises a scanner adapted for successively scanning the condition of a plurality of switches adapted to be individually operated in response to depression of the keys of a keyboard of a musical instrument, means connected to the scanner and operative to provide an indication of which key of those depressed corresponds to the tone having the highest pitch of any of the depressed keys, and means for automatically generating a harmony in a plurality of individual voices below said highest tone in response to one or more additional keys simultaneously depressed, each of said individual voices being selected only in response to the relative pitches of said tones.

It is accordingly a principal object of the present invention to provide an electronic musical instrument having means for generating a plurality of harmonizing tones which does not require a multiplicity of separate switches or switch poles for each key.

Another object of the present invention is to provide apparatus for generating such tones which has a simplified construction.

A further object of the present invention is to provide means for sounding a plurality of tones below the highest pitch tone played in response to depression of a key of a solo keyboard, the relationship of the voices such tones being automatically selected in accordance with the relative pitch of such tones.

A further object of the present invention is to provide a harmony generator adapted for sounding a plurality of tones forming a chord in response to depression of 2 certain keys of a solo keyboard and an accompaniment keyboard, in which the key for the tone having the highest pitch is sounded in a first predetermined voice, and the key for the tone having the second highest pitch is sounded in a second predetermined voice, irrespective of which tones are sounded.

These and other objects and advantages of the pres ent invention will become manifest upon an examination of the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Reference will now be made to the accompanying drawings in which:

FIG. 1 is a functional block diagram of a portion of an electronic musical instrument incorporating an illustrative embodiment of the present invention;

FIG. 2 is a functional block diagram of certain portions of the apparatus of FIG. 1, shown in more detail;

FIG. 3 is a schematic circuit diagram of a diode selection matrix employed in the apparatus of FIG. 1;

FIGS. 4 and 5 taken together comprise a functional block diagram of a logic control unit embracing several of the functional units employed in the apparatus in FIG. 1;

FIG. 6 is a functional block diagram of a plurality of note selectors and dividers employed with the apparatus of FIG. 1;

FIG. 7 is a schematic circuit diagram of an illustrative keyer which may be employed with the apparatus of FIG. 1;

FIG. 8 is a functional block diagram of an alternative arrangement which may be employed with the apparatus of FIG. 1 in an alternative embodiment of the present invention; and

FIG. 9 is a series of wave forms forming a timing diagram illustrating the sequence of certain operations within the system.

In FIG. I, which is a functional block diagram of an illustrative embodiment of the present invention, a clock pulse generator 10 generates a succession of clock pulses and applies such pulses over an output line 12 to the input of a divide-by-twelve unit 14. The divide-by'twelve unit 14 comprises a four stage binary counter, and four output lines lS-l8 connect the output terminals of the divide-by-twelve unit 14 to four inputs of a.note decoder unit 20, which comprises a l-of-12 decoder. The twelve output lines 22 leading from the note decoder 20, which are energized individually in response to unique combinations of high and low potentials on the lines 15-18, are illustrated as a single line in FIG. I in the interest of simplifying the drawings. The number of separate lines represented by the line 22 is indicated parenthetically. The same is true for the other muIti-conductor lines of FIG. I.

The output line 18 of the divide-by-twclve unit 14 is connected to the input of a divide-by-four unit 24. The divide-by-four unit 24 is a two-stage binary counter which produces output signals on two output lines 26 and 28. The lines 26 and 28 are connected to the two inputs of an octave decoder unit 30, which produces signals on four output lines 32. The decoder unit 30 is a one-of-four decoder, so that one of the four lines 32 is energized, in accordance with the potentials on the lines 26 and 28.

Outputs of the decoders 20 and 30 are supplied, respectively, to lines 34 and 36, which are connected to the inputs of a synchronization decoder 38. The de- 3 coder 38 produces pulses on two output lines 40 and 42 in response to unique combinations of output signals produced by the decoders 20 and 30. The pulses on the line 40 and 42 are used for synchronization purposes, as more fully described hereinafter, and are applied respectively to inputs of a plurality of latches within a latch unit 44, to an input of a priority logic unit 46, and to the window logic unit 58.

The twelve output lines 22 of the note decoder 20 and the four output lines 32 of the octave decoder 30 are applied to inputs of a selection matrix 48, which is adapted to produce output signals on two output lines 50 and 52. The matrix is connected by lines 49 to 37 individual switches controlled by the keys of the upper manual (or solo) keyboard, and by twelve lines to the switches operated by the keys of the lower manual (or accompaniment) keyboard.

The output line 50 is connected to the input of a shaper unit 54, and the output of the shaper unit 54 is connected over a line 56 to the input of a window logic unit 58. The pulses supplied to the logic unit 58 over the line 56 correspond to operated keys of the upper manual of the instrument. The output line 52 is connected through a shaper unit 60, and the output of the shaper unit 60 is connected over a line 62 to the input of an AND gate 64. The pulses on the line 62 are representative of the operated keys of the lower manual of the instrument, and of all other keys which are octavely related thereto. The shapers 54 and 60 are preferably AND gates of the saturated logic type, such as transistor transistor logic (TTL), so that they inherently function as shapers to produce a rectangular pulse output in response to an input pulse.

An output of the window logic unit 58 is connected over a line 68 to a second input of the AND gate 64, and the AND gate 64 provides input signals to the priority logic unit 46 over a line 66. The window logic unit 58, together with part of the matrix 48, forms a first scanning means for scanning the upper manual keys, while the gate 64, together with another part of the matrix 48, forms a second scanning means for scanning the keys of the lower manual.

The function of the window logic unit 58 is to identify the uppermost key (i.e., the key corresponding to the tone of highest pitch) depressed by the operator, and to provide a signal on the line 68 corresponding to a window through which up to twelve pulses may be passed through the AND gate 64, from the line 62 to the line 66. The pulses present on the line 62 are representative of all keys octavely related to the depressed keys in the lower manual, so that the pulses produced on the line 66 are representative of the keys of the upper manual which are octavely related to depressed keys of the lower manual, and which are within the window, i.e., within the first twelve pulse times following the first pulse present on the line 56. The window logic unit 58 has an input from the line 42 in order to synchronize its operation and another input to the clock generator over a line 59.

The priority logic unit 46 is also connected to the line 42 for synchronization purposes. It produces four signals on output lines 70, which are connected to the latch unit 44. An output latch within the unit 44 produces a signal which identifies which of the other latches within the unit 44 are set during each cycle of operation, and when such setting occurs. Periodically, the output latch is reset by a signal provided thereto over the line 40. When the latches are set, they are 4 each set in accordance with the simultaneous levels present on the lines l5l8, via four input lines 45, and on the lines 26 and 28 via two additional input lines 47.

Twenty-four output lines are connected to the latches 44, and these 24 lines are represented by a line 78 interconnecting the latches 44 to a selector and divider unit 74, which incorporates a number of selectors and dividers. The selectors and dividers are connected to a signal generator 76 over a plurality of twelve lines 77. The tone signal generator 76 produces on each of its l2 output lines a signal having a frequency which corresponds to a harmonic of the frequency of one of the 12 notes of the chromatic scale, and selectors and dividers 72 manipulate such signals, in response to the signals received from the latches 44 over the lines 78, to provide signals on 16 output lines 80. The 16 output lines 80 are connected to inputs of a keying unit 82 incorporating a plurality of keyers, which also receive four inputs over lines 84 from the latches 44. The keyers are connected to a voicing unit 86 incorporating a plurality of voicing circuits by four lines 88. When a composite voice is desired, several lines 88 may be provided for each keyer. The voicing circuits within the unit 86 are selected by means of signals produced by an orchestration control unit 90, interconnected with the voicing unit 86 over lines 91. The voicing circuits are connected with an output terminal 92, which is adapted to be connected to the output system of the electronic musical instrument for producing tones in accordance with the output signals of the voicing circuits. The four signals produced as outputs from the keyers 82 correspond with four tones ofa chord selected by depressing four keys of the lower manual, and each tone is separately voiced by means of the voicing circuits 86 before being connected to the output system via the terminal 92. One signal is produced from the keyers 82 for each key which is depressed, so that less than four signals are produced if less than four keys are depressed.

In FIG. 2 a more detailed functional block diagram of certain portions of the apparatus of FIG. I is illustrated. The clock generator 10 incorporates an oscillator 94 which is conveniently an astable multivibrator having a period determined by the time constant of an RC circuit including a resistor 96 and a capacitor 98. The oscillator 94 furnishes an output on a line 97 which is connected to the toggle input of a flip-flop 98. The flip-flop 98 furnishes a clock signal on an output line 12 which is connected to the input of the divide-by-twelve unit 14 and also to a line 59, which is connected to other points throughout the system where clock pulses are needed.

The clock pulse generator illustrated in FIG. 2 is conventional, and may readily be formed of conventional components. For example, the oscillator 94 preferably comprises a type 8601 multivibrator. The flipflop 98 preferably comprises a .l-K flip-flop, such as one-half of an integrated circuit type 74107, having its J and K input terminals connected to a positive potential via a resistor I00, and its clock input connected to the line 97. By use of the flip-flop 98, the clock signal applied to the line 12 and 59 is made a square wave, having equal positive-going and negative-going portions although the output of the oscillator 94 has a less symmetrical waveform.

The divide-by-twelve unit 14 is preferably a unit such as a type 7493 (nominally a four-stage binary counter) with two of its outputs connected to inputs to reduce the radix of the counter from sixteen to twelve.

The four outputs made available on the output lines -18 are the four outputs produced individually by the four binary stages of the counter. One is connected to the divide-by-four unit 24 over a line 106. The divide-by-four unit comprises a pair of J-K flip-flops, both having their .1 and K inputs connected to a source of positive potential through a resistor 108. The clock input of the first flip-flop is connected to the line 106, and the clock input of the other flipflop is connected to the Q output of the first flip-flop. The Q outputs of the two flip-flops are connected over lines 26 and 28 to terminals 110 and 112, respectively. In addition, the 6 outputs of the two flip-flops are connected to lines 114 and 116. The lines 26, 28, 114, and 116 are connected in unique combinations to the inputs of four NOR gates which comprise the octave decoder 30. The NOR gate 118 has its inputs connected to the lines 26 and 28; the NOR gate 120 has its inputs connected to the lines 28 and 114; the NOR gate 121 has its inputs connected to the lines 26 and 116; and the NOR gate 122 has its inputs connected to the lines 114 and. 116. The NOR gates 118-122 produce an individual output at four output terminals 123-126.

The four output lines 15-18 of the divideby-twelve unit 14 are connected to the four inputs of the note decoder 20. The note decoder incorporates a l-of- 12 decoder 128 which may be formed of a conventional integrated circuit unit such as type 8311. Six of the twelve outputs 132 of the decoder 128 are connected to six input terminals of a group of six inverters 130 which functions to individually invert the signals present on six of the lines 132 and to convey them individually to six of the output lines 22. The other six of the twelve output lines 132 from the decoder 128 are connected to six inputs of a second group of six inverters 134, and they are thereby inverted and presented to the other six of the output lines 22. The 12 output lines of the inverters 130 and 134 are each associated with a different note of the chromatic scale, as illustrated in FIG. 2, for a purpose more fully described hereinafter.

Two of the outputs of the inverter unit 134 are connected individually to two AND gates 136 and 138, both of which have their second inputs connected to the output of the NOR gate 122 of the octave decoder unit 30. The gates 136 and 138 are operative to produce output signals on lines 40 and 42 for synchronization purposes. The line 40 is connected to a terminal 140 and the line 142 is connected to a terminal 142. The terminals 140 and 142 are connected to various points within the system where the synchronization pulses supplied thereto are required.

Referring now to FIG. 3, which is an illustration of the diode matrix incorporated in the apparatus of FIG. 1, the 12 lines 22 are connected from the inverters 130 and 134 (FIG. 2) to twelve parallel lines of the matrix 144a-144n. The line 144a will sometimes be referred to hereinafter as the "C" line, the line 144b as the 8" line, and so on, with the line 144n being referred to as the "C# line. These lines are energized in succession by the operation of the decoder 20, so that only one of the line 144a-l44n at a time has a high potential thereon.

The C line 144a of the matrix is connected through a diode 158 and a resistor 160 to a terminal U-37, which is adapted to be connected to the normally open contact of a key operated switch 149 associated with the highest C key of the upper manual keyboard. When that key is depressed, the switch functions to apply high potential to the terminal U-37. This high potential permits the line 180 to go high, via a diode 171, provided that the C input line 22 is high, and also provided that the line 180 is not clamped to a low potential via the terminal 123, as more fully described hereinafter. The C line 1440 is also connected to a terminal U-ZS through a diode 154 and a resistor 156, and to a terminal U-13 through a diode I50 and a resistor 152. In a similar fashion, the C line 144a is connected to a terminal U-l through a diode 146 and a resistor 148. The U-25 terminal is connected to a switch actuated by the second highest C-key of the upper manual keyboard, and the U-13 and the U-1 lines are connected to the key operated switches of the next two lower C keys of the upper manual. Depression of the key associated with the terminal U-25 causes the line 174 to go high when the C line 144a and the terminal 124 are both high. Depression of the other C keys has a similar effect on lines 162 and 165, provided the lines 126 and are high, respectively.

In similar fashion, the B line 144!) is connected in circuit to a terminal U-36 through a diode 173 and a resistor 175, corresponding to the diode 158 and the resistor 160, and also to the terminals U-24 and U-12 through corresponding diodes and resistors. The terminal U-36 goes high whenever the highest one of the B keys of the upper manual is depressed, resulting in a high potential on the line 180 when the line 144!) is high, provided that the terminal 123 is also high. The other B terminals U-24 and U-12 are connected in similar fashion, as are all of the other terminals U-l, U-37, which correspond to the 37 lines 49 of FIG. 1.

The terminal U-I is also connected through a diode 161 to the line 162, and the line 162 is connected through a diode 164 to the terminal 126 (FIG. 2) and through a diode 166 connected in series with a resistor 168 to ground. The line 162 is referred to hereinafter as the lower octave" line, and its level goes high whenever the key connected with the terminal 11-1 is depressed, to connect a high potential through the resistor 148 and the diode 161, provided there is at that time a high potential on the terminal 126. As described above, the terminal 126 is connected to an output of the octave decoder 30, and the terminal 126 is rendered high only when both inputs to the NOR gate 122 are low. This occurs during each cycle during an interval devoted to decoding the notes of the lowest octave of the instrument.

The 12 terminals U-2 through U-13 are each connected through an individual diode like the diode 163, to the line 165. The diode 163 is connected from the U-2 input resistor 164 to the line 165. The line 165 is connected through a diode 167 to the terminal 125 and through a diode 170 to a point 172, located at the junction between the diode 166 and the resistor 168. The line 165 goes high whenever a key within the first octave above the lowest octave of the instrument (namely, the keys corresponding to the terminals U-2 U-l3) is depressed, provided that the terminal 125 is high. The terminal 125 goes high when the second highest octave is being scanned, at which time the inputs to the two inputs of the NOR gate 121 are both low.

The remaining two octaves of the upper manual are similarly treated. The switches associated with the terminals U-IS to U-25 are connected through diodes to the line 174, and the line 174 is connected to the termiha] 124 through a diode 176 and through a diode I78 to the point 172. Similarly, the switches of the highest octave of the upper manual, corresponding to terminals U-26 U-37, are all interconnected through individual diodes to the line 180, which is connected by a diode 182 to the terminal 123 and by a diode 184 to the point 172. The diodes 166, 170, 178, and 184 all pass positive potentials to the point 172, from their respective lines 162, 165, 174, and 180, whenever, during the interval devoted to each respective octave, a key within such octave is simultaneously depressed. There is, therefore, present at the point 172 a train of pulses corresponding to every depressed key of the upper manual, with the time position of each such pulse corresponding to one particular key.

The arrangement of the connections between the octave decoder 30 and the divideby-four unit 24 is such to energize the four output terminals 123-126 in sequence, with the output terminal 123 being energized first, followed in order by the terminals 124, 125, and 126.

The point 172 is connected to the base ofa transistor 186, the emitter of which is connected to ground through a resistor 188, and the collector of which is connected to a source of positive potential by a line 190. The emitter is also connected to the output line 50, so that a pulse train of positive pulses is presented on the line 50, corresponding to actuated ones of the keys of the upper manual, such pulses being encoded in time position.

An additional set of twelve input terminals 51 is provided for the matrix 48, and each of the terminals 51 is associated with a series of octavely related keys of the lower manual. The terminal identified as LC is supplied with a positive potential whenever any C key of the lower manual is actuated, and is conveniently connected with a plurality of switches 198 operated individually by the C keys of the lower manual, with all of such switches being connected in parallel between a source of positive potential and the terminal LC. Thus, the terminal LC receives a positive potential whenever any C key is depressed in the lower manual. Similarly, the terminal LB is supplied with a positive potential whenever any B key of the lower manual is depressed, and the same is true for the other terminals 51.

The terminal LC is connected through a resistor 200 and a diode 202 to the C line 144a The terminal LC is also connected through the resistor 200 and a diode 204 to a line 206, which is connected to ground through a resistor 208. The LB terminal is connected through a resistor 210 and a diode 212 to the B line 1443, and through the resistor 210 and a diode 214 to the line 206. The remainder of the twelve input terminals 51 are also connected through individual diodes to the line 206, and through individual diodes to individual ones of the line 144c-l44n. Only one of the twelve lines 144a-l44n is high at any given time, and the others are clamped to ground. Accordingly, the positive signals applied to the terminals 51 are clamped to ground through the resistors 200, 210, etc., except when the corresponding line 144a-144n is supplied with a high potential over one of the lines 22. Accordingly, when one of the lines 1440-14411 is high, if any corresponding key of the lower manual is depressed, the line 206 goes high, to produce a positive-going pulse. Accordingly, the line 206 is provided with a pulse train corresponding to the operated keys of the lower manual, such pulse train being repeated for each of the several octaves which are scanned.

The line 206 is connected to the base of a transistor 216, the collector of which is connected by the line to a source of positive potential. The emitter of the transistor 216 is connected to ground through a resistor 218, and is also connected to the output line 52. Accordingly, the output line 52 is supplied with a train of pulses corresponding to operated ones of the keys of the lower manual. The pulse trains present at the two output terminals 50 and 52 thus correspond respectively to the actuated keys of the upper and lower man uals.

Referring now to FIGS. 4 and 5, which together make up the logic unit employed, the upper manual pulse train is applied from the terminal 50 through the AND gate 54 to the line 56. Similarly, the lower manual pulse train is applied from the terminal 52 through an AND gate 60 to the line 62. The line 56 is connected to the J input of a .I-K flip-flop 222, which has its clock input connected to the line 59 (FIG. 2) over a line 224. The K input terminal is connected to the terminal 142 (FIG. 2) over a line 226, to receive synchronization pulses therefrom.

The pulses present at the terminal 142 operate to reset the flip-flop 222, and signals applied to the J input over the line 56 function to set the flip-flop 222, at the time of the next concurrent clock pulse applied to the line 224. The 6 output of the flip-flop 222 is connected over a line 228 to the input of an AND gate 230, which has its second input connected to the line 56. The AND gate 230 is normally in condition to pass pulses from the line 56 to the input of a ten bit shift register 232. Only the first pulse is passed, however, since the first pulse operates to set the flip-flop 222, after which a low potential is present on the line 228 and the gate 230 is disabled. The output of the shift register 232 is connected to the input of a two bit shift register 234. Both shift registers 232 and 234 are supplied with clock pulses by being connected to the line 59 via an inverter 236. The shift register 232 is preferably an integrated circuit unit such as a type 8273, and the shift register 234 is preferably a unit such as the type 7479.

The output of the shift register 234 is passed through a capacitor 240 and a resistor 242 to ground. The circuit including the capacitor 240 and the resistor 242 forms a differentiating circuit, and positive-going pulses passed by the capacitor 240 are connected by a diode 244 through a resistor 246 to ground. The junction of the diode 244 and the resistor 246 is connected to the input of an inverter 248, the output of which is connected to the reset input of an RS flip-flop 250. The input of the inverter 248 is also connected through a diode 252 to the output of a differentiator circuit including a capacitor 254 and a resistor 256, the input of which is connected to the line 226. Thus a positivegoing input on the line 226 (from the terminal 142) and a positive-going output pulse from the shift register 234 both serve to produce a negative pulse at the output of the inverter 248.

The output of the AND gate 230 is connected by a line 258 to the input of an inverter 260, the output of which is connected to the set input of the RS flip-flop 250. The line 258 passes the first pulse presented to the terminal 50, corresponding to the highest operated key of the upper manual. This pulse is inverted by the inverter 261 and passed to the RS flip-flop 250, and thus serves to set it into a state in which an output line 68 goes high. The flip-flop 250 has previously been reset, at the beginning of the cycle, by a positive-going pulse 9 applied to the terminal 142. The flip-flop 250 is again reset when the output of the shift register 234 goes high, which occurs twelve pulse times after the first pulse appears at terminal 50. Thus, the line 68 is high only for twelve pulse times, beginning with the first pulse applied to the terminal 50.

The line 68 is connected to the AND gate 64, as is the line 62, leading from the output of the shaper AND gate 60. The input of the shaper 60 is connected to the terminal 52, to which is supplied the lower manual pulse train. Accordingly, the gate 64 is able to pass pulses from the terminal 52 to its output line 66 only during the twelve pulse times when the line 68 is high. This corresponds to the twelve pulse times representative of the first octave below the highest operated key of the upper manual.

The pulses present on the line 66 are connected to the J input of a .l-K flip-flop 260 and to one input of the AND gate 262. The K input terminal of the flip-flop 260 is connected to terminal 142 for resetting the flipflop 260 at the beginning of each cycle, and the clock terminal is connected to the terminal 59. The first pulse which arrives on the line 66 during each cycle is therefore effective to set the flip-flop 260, causing its output terminals to be reversed with the trailing edge of the clock pulse which is coincident with the first pulse occurring on the line 66. The 6 output of the flip-flop 260 is connected to an input of an AND gate 264, the second input of which is connected to the line 66, and the Q output of the flip-flop 260 is connected to the second input of the AND gate 262. The 6 output is high when the flip-flop 260 is in its reset condition, and therefore the AND gate 262 is enabled to pass the first pulse, with subsequent pulses being passed by the AND gate 264, after the flip-flop 260 has been set. The output of the AND gate 262 is connected to one input of an AND gate 266, the second input of which is connected from the output of an AND gate 268. The line 59 is connected through a shaper unit 272, and the output of the shaper unit 272 is connected in common to two input terminals of an AND gate 274, which also functions as a shaper. The outputs of the shaper 272 and 274 are connected to ground respectively by capacitors 276 and 278, and the output of the shaper 274 is also connected in common to two inputs of an AND gate 268, which functions as a further shaper. The capacitors 276 and 278 function as a delay mechanism so that clock pulses appear at the output of the gate 268 slightly delayed in time from their appearances on the line 59.

The AND gate 266 produces a high output on the line 280 only when high signals are simultaneously presented to its two inputs. Because of the delay introduced by the shapers 274 and 268, the duration of the output pulse presented by the gate 266 to the line 280 is relatively short, and occurs only during the intervals when the levels in the lines 45 and 47 are constant, i.e., when they are not changing.

The line 280 is connected to the strobe inputs of two latches 282 and 284. The latch 282 is preferably onehalf of an integrated circuit, such as one-half of a type 7475, and the latch 274 is preferably a full unit, such as a type 7475. The two data input terminals of the latch 282 are connected from the terminals 110 and 112 which are the two outputs 47 of the divide-by-four unit 24, and are energized in accordance with the binary representation of the octave being scanned at any given time. The condition of the terminals 110 and 1 12 which 10 is present at the time that a pulse appears on the line 280 is stored in the latch 282, and thereafter is continu ously manifested by its output terminals 286 and 288. Thus, a representation of the octave during which the latch 282 was last operated by a pulse on the line 280 is manifested by the output terminals 286 and 288.

The four data input terminals of the latch 284 are connected to the terminals 15-18 which are the four outputs 45 of the divide-by-twelve counter 14(FlG. 2)v These outputs present a binary representation of the note being scanned at any given time. The latch 284 operates in the same manner as the latch 282, and manifests on its four output terminals 290-293 the binary representation of the note which was being scanned at the time the latch was last set by a pulse appearing on the line 280. Such manifestation is main tained until such time as a subsequent pulse appears on the line 280. It is apparent that no pulse can occur subsequently on the line 280 until the flip-flop 260 has been reset, thus enabling the gate 262 to pass pulses from the line 66.

The second pulse appearing on the line 66 is passed through the gate 264 to the J input terminal of a flipflop 294. The flip-flop 294 has its clock input terminal connected to the terminal 59 and its K input terminal connected to terminal 147. It is set by the first pulse appearing on the line 293, at the output of the AND gate 264. The 6 output of the flip-flop 294 is connected to one input of an AND gate 296, the other input of which is connected to the line 293. The output of the gate 296 is connected to one input of an AND gate 298, the second input of which is connected to the output of the AND gate 268. The output of the AND gate 298 is connected to the strobe inputs of two latch units 300 and 302, by a line 301, which latch units are identical in construction and operation to the units 282 and 284, respectively. The data input terminals of the latch 300 are connected to the terminals and 112, and the data inputs of the latch 302 are connected to the terminals 15-18, in parallel with corresponding connections of the latches 282 and 284 described above. Accordingly, the second pulse on the line 66, which is the first pulse on the line 293, functions to set the latches 300 and 302, to present at their output terminals, 303-304 and 305-308, respectively, the binary representations of the octave and note being scanned at the time of occurrence of the second pulse on the line 66.

Another flip-flop 310 is connected in the same manner as the flip-flops 260 and 294, and functions to cause latches 314 and 316 to be set by a pulse on a line 315, so that they produce outputs which are the binary representation of the octave and note being scanned at the time that the third pulse appears on the line 66. A fourth flip-flop 312 is similarly connected via line 319 to set the latches 318 and 320, to cause them to manifest outputs representative of the octave and note being scanned at the time of the fourth pulse arriving on the line 66.

The Q outputs of the four flip-flops 260, 294, 310, and 312 are each connected to one of the four data inputs of an output latch 322, the strobe input of which is connected to the terminal (FIG. 2). A pulse appears at the terminal 140 a short time before the pulse occurs at the terminal 142, so that the latch 322 is energized with the binary representation of the Q outputs of the four flip-flops 260, 294, 310, and 312 during the end of the scanning cycle. In this way, data is stored in the latch 322 corresponding to which of the several latches have been set during the preceding cycle. This data is employed to operate only the keyers which are necessary to handle the data stored in the several latches, and to avoid operation of keyers in response to obsolete data which may remain manifested by one or more latches as a result of a previous cycle of operation. Such binary representation is applied to the keyer in the manner described hereinafter.

Referring now to FIG. 6, a one-of-twelve selector 326 has its four control terminals connected to the terminals 290-293 from FIG. 4. The data input terminals are connected to twelve lines 77 which are connected to a frequency synthesizer unit, or the like, which is adapted to produce, on the twelve lines 77, signals having frequencies which are harmonics of the twelve notes of the chromatic scale. All of the tones to be reproduced by the electronic musical instrument may be derived from the signals present at the terminals 77 by dividing the pulse repetition rate of such signals. The pulse repetition rates of the signals present at the terminals 77 are preferably the second harmonics of the highest desired frequencies, so that the signals required for the production of the tones of the top octave of the musical instrument are derived by dividing the pulse repetition rate of the signal present on the terminals 77 by a factor of two. The frequencies required for the next lower octave are derived by dividing the frequencies of the signals on the terminals 77 by a factor of four. Lower octaves are treated in the same way, using different divisions.

The l-of-l2 selector 326 is adapted to connect one of its twelve data inputs to an output line 330, in accordance with the binary representation present on its control terminals 290-293. For example, when low potentials are present at all four terminals 290-293, a first one of the twelve input lines 77 is selected. When the terminals 290-292 are low and the terminal 293 is high, a second one of the terminals 77 is selected for connection to the output line 330, and so on. in this manner, one of the twelve terminals 77 is connected to the output line 330 in response to the manifestation of the outputs of the latch 284 (FIG. 4), which stores a binary representation of the note represented by the first pulse appearing on the line 66.

The line 330 is connected to the input of a four-stage binary counter 332 which is operative to divide the pulse repetition rate of the signal present on the line 330 by powers of two. An output line is connected to the output of each of the four stages of the unit 332. An output line 334 is connected to the output of its first stage; an output line 336 is connected to the output of its second stage; and output line 338 is connected to the output of its third stage; and an output line 340 is connected to the output of its fourth stage. The four outputs 334-340 of the unit 332 produce pulse trains in response to the pulse train present on the line 330, but having reduced pulse repetition rates. The signal pres ent on the line 334 has one-half the pulse repetition rate of that present on the line 330; the pulse repetition rate of the signal on the line 336 is one-fourth of that present on the line 330, and so on. Thus, the four lines 334, 336, 338, and 340 represent four different octaves.

The lines 334-340 are connected to four inputs of a l-of-4 selector unit 342, which functions in a manner similar to the unit 326, to connect one of its data input lines 334-340 to an output line 344, in response to the signal supplied to its control input terminals 286, and 288, which are the output terminals of the latch 282, which stores a binary representation of the octave corresponding to the note represented by the first pulse present on the line 66 (FIG. 4). If the first pulse arrives on the line 66 during the time that the top octave is being scanned, the signals present at the terminals 286 and 288 cause the unit 342 to select the line 334 for connection to the output line 344. If the second highest octave is the one being scanned when the first pulse appears on the line 66, the potential levels at the terminals 286 and 288 are different, and cause the selector unit 344 to select the line 336 for connection to the output line 344. In similar fashion, if either of the two lower octaves correspond to the octave of the note represented by the first pulse to arrive on the line 66, one of the lines 338 and 340 is selected by the unit 342 for connection to the output line 344.

The line 344 is connected directly to an output terminal 348 by a line 346, and to three additional output terminals 349, 350 and 351, via a three-stage binary counter 354. The counter 354 functions in the same manner as the counter 332, except that only three output lines are provided, one from each of three stages of the counter. The output lines are connected to the terminals 349-351, and furnish signals thereto which have pulse repetition rates which are derived from the signal on the line 344 by dividing the pulse repetition rate thereof by powers of two. The output of the first stage of the counter 354 is connected to the terminal 349; the output of the second stage is connected to the terminal 350; and the output of the third-stage is connected to the terminal 351.

The pulse repetition rate of the signal present at the terminal 349 is, therefore, half of that present at the terminal 348, and the pulse repetition rates of the signals present at the terminals 350 and 351 are, in each case, half that of the pulse repetition rate applied to the preceding output terminal. The terminal 348 may be referred to as the 2-foot" output terminal. The terminal 349 may be referred to as a 4-foot output terminal. Similarly, the terminals 350 or 351 may be referred to as the 8-foot" and l 6-foot" output terminals, and are similarly connected. The four terminals 348-351 are connected by means of a keying unit within the group of keyers 82 (FIG. I) to a voicing unit within the group 86.

The voicing unit may be of any known type, such as clarinet, horn, or the like, with the output of the voicing unit connected to the output system of the musical instrument in the conventional manner. The l-of-l2 selector 326 is preferably an integrated circuit such as a I50, and l-of-4 selector is preferably an integrated circuit such as a 74151. The dividers 332 and 354 are conventional binary counters, with an output terminal connected to each stage thereof.

A second l-of-l2 selector 356 has its control input terminals connected to the terminals 305-308 (FIG. 5), which manifest the binary representation of the note corresponding to the second pulse appearing on the line 66. The data input terminals of the unit 356 are connected in common with those of the unit 326, so that one of the twelve signals presented to the terminals 77 is connected to the output line 358 of the unit 356, in accordance with the condition of the control terminals 305-308. A four-stage binary counter 360 has its input connected to the line 358 and supplies output signals on four lines 361-364, which differ in their pulse repetition rates by powers of two, just as described in connection with the counter 332. The 1-of-4 selector 366 has its four data input terminals connected to the lines 361-364, and its two control input terminals connected to the terminals 303 an 304, which manifest the binary representation of the octave stored in the latch 300, corresponding to the octave of the second pulse appearing on the line 66. One of the four data inputs of the unit 366 is connected to its output line 368, which is connected to the input of a threestage binary counter 370. The line 368 is connected by a line 372 directly to a terminal 374, and the outputs of the stages of the counter 370 are connected to the terminals 375-377. The output terminal 374 is the 2-foot" output terminal; the output terminal 375 is the 4-foot" output terminal; the output terminal 376 is the 8-foot output terminal; and the terminal 377 is the 16-foot output terminal. Their operation and function is the same as described in :connection with the units 332, 342, and 354.

The second pulse to appear on the line 66 corresponds to the second key of the lower manual to be encountered during the downward scan of such keys. Accordingly, the frequency selected by means of the bot-4 selector 356 corresponds to a harmonic of the tone corresponding to the second pulse appearing on the line 66. The octave in which such tone is being played, as indicated by the condition of the latch unit 300 (FIG. controls the potentials applied to the control inputs 303 and 304 of the selector 366, so that the signals presented at the output terminals 374-377 correspond to four different footages of a second note being played by depressing a key of the lower manual. The output terminals 374377 are connected to a voicing unit different from that to which the output terminals ar the unit 354 is connected, and this second voicing unit has its output connected in common with the output of the first voicing unit at the input terminal of the output system of the musical instrument. Two additional l-of-12 selector units 378 and 380 are illustrated in FIG. 6, each of which have their data inputs connected in common with the data inputs-of the units 326 and 356, and their control inputs connected to the outputs of the latches 316 and 320, respectively. The units 378 and 380 are both connected successively to a four-stage binary counter, a 1-of-4 selector, and a three-stage binary counter,just as described above with reference to the selector units 326 and 356. A set of four output terminals 382 is energized in response to operation of the system connected with the selector unit 378, and an additional set of four output terminals 384 is energized in response to operation of the system connected with the selector unit 380. The signals presented to the output terminals 382 and 384 represent the various footages of the third and fourth notes of the chord selected by depression of the keys on the lower manual. Each of these terminals is connected by means ofa tab switch, or the like, to the inputs of third voicing first voice, i.e., that produced in response to the output terminals 348-351, always corresponds to the highest note of a chord selected on the lower manual which is below a note octavely related with the highest note being played on the upper manual at any given time. In other words, the first voice is always the highest voice below the top solo note. Accordingly, a melody can be readily played with a single note at a time on the upper manual, such note being sounded in a normal solo voice being selected by means of tab switches, or the like, in the conventional manner, and up to four additional notes are sounded within the first octave below such single note, each of the additional notes being sounded in an independent voice, with the first one below the single note being sounded in the first voice, the second in the second voice, and so on. When the voices of the notes selected in response to operation of the keys of the lower manual are employed with voicing units representing a clarinet, a horn, and two other individual voices, the net effect of operation of the system is to simulate the simultaneous reproduction of a number of instruments, each playing a separate part of the harmony, with each part maintained in the same relation to the other parts.

The particular voicing units which are employed with the system of the present invention may be selected from any known or commercially available voicing units, so that they need not be described in detail therein.

FIG. 7 illustrates a schematic circuit diagram of a keyer unit which may be employed for interconnecting the four outputs 348-351 with four inputs of a voicing unit. The four terminals 348-351 are each connected to the cathode of an individual one of four diodes 386-390. The anodes of the diodes 386-390 are each connected, respectively, through four diodes 391-394, and through an individual voltage divider, incorporating a pair of resistors 395 and 396, to ground. The outputs of the four voltage dividers are connected by lines 397 individually to four output terminals 398-401. The junction between the diodes 386 and 391 is connected by a resistor 402 to a line 403, and the junction of each of the other pairs of diodes is connected to the line 403 through individual resistors 404, 405 and 406, respectively. The diodes 386 and 391 are connected with their anodes in common so that a current which passes one of the diodes is blocked by the other. When, however, a positive potential is applied to the line 403, both of the diodes are forward biased, so that a signal applied to the terminal 348 causes a corresponding signal to be produced at the output terminal 398. When the potential on the line 403 is low, however, the connection between the input terminal 348 and the output terminal 398 is effectively blocked by the reverse poled diodes 386 and 391.

The control circuit for controlling the potential on the line 403 includes a pair of transistors 408 and 410. An input signal applied to an input terminal 414 is connected through a resistor 415 to the base of the transistor 408, which has its collector connected to a source of positive potential at a terminal 416, through a pair of series connected resistors 418 and 420. The junction of the resistors 418 and 420 is connected to the base of a pnp transistor 410, which has its emitter connected to a positive potential at a terminal 416 and its collector connected through a resistor 422 to ground. lts collector is also connected through a diode 424 to the line 403. Accordingly, when a positive po tential is applied to the input terminal 414, the transistors 408 and 410 both become conductive, the voltage across the resistor 422 increases, and the potential on the line 403 increases correspondingly. A capacitor 426 is connected from the line 403 to ground to maintain the potential on the line 403, until the charge on the capacitor 426 is dissipated through the circuit connected in parallel therewith, which includes the voltage divider resistors 395 and 396.

The input terminal 414 is connected to one of the four output terminals 324 of the latch unit 322 (FIG. 5), and particularly to the one which goes high in response to a signal developed at the 0 output of the flip-flop 260 (FIG. 4), signifying that the flip-flop 260 has been set during the current cycle of operation, beginning with a pulse at the terminal I40 which clears the latches of the latch unit 322. The latch unit 322 is preferably an integrated circuit such as type 7475, like the other latches described above. Other keyers like that shown in FIG. 7 are connected to receive the other three sets of outputs from FIG. 6, (viz., 374-377, 382, and 384), and each of such other keyers is controlled with appropriate ones of the outputs 324 from the latch unit 322, so that only the keyers associated with notes occuring in the current cycle are activated. The clear pulse applied to the latch unit 322 at the beginning of each cyclefunctions to disable the unused keyers.

The line 403 is connected through a diode 428 and a resistor 430 to a control terminal 432, which is adapted to be connected to ground when a more rapid discharge of the capacitor 426 is desired. When the potential at the terminal 432 is high, the diode 428 is blocked, and the rate at which the capacitor 426 is discharged is controlled by the resistance of the voltage divider circuits. When the potential at the terminal 432 is low, the rate of discharge of the capacitor is controlled only by the relatively low value of the resistor 430.

As described above, the present invention is adapted to select the four notes of the harmonizing chord within the twelve notes immediately below the top note selected by depression of a key of the upper manual. There are occasions, however, when it is desired that the first or second note below the top note selected on the upper manual should not be selected, so as to avoid creating an undesired dissonance. Accordingly, it is, in certain conditions, desirable to prevent selection of the first few notes below the highest selected note of the upper manual. Such notes correspond to the pulses which are received within the first few pulse times following the setting of the flip-flop 232 (FIG. 4), which is set in response to detection of the highest selected note of the upper manual.

The circuit for accomplishing this function is illustrated in FIG. 8. FIG. 8 includes a portion of the apparatus illustrated in FIG. 4, and the apparatus which is unmodified is indicated by the same reference numerals. The structure of FIG. 8 which is not illustrated in FIG. 4 includes a single pole, double-throw switch 440 and a single pole, triple-throw switch 442. The common terminal of the switch 440 is connected to the line 258, and the common terminal of the switch 422 is connected to the capacitor 240. The left-hand contact of the switch 440 is connected to the output of the AND gate 230, and the right-hand contact is connected to the 0-! output of the I0 bit shift register 252.

The three contacts of the switch 442 are connected, respectively, to the 0-10 output of the IG bit shift regis- 16 ter 252, the 0-! output of the two bit shift register 234, and the 0-2 output of the 2 bit shift register 234.

The switch 440 is operative to select a pulse for set ting the RS flip-flop 250. When the switch is in its left-hand position, the operation is in the same as that described above. When the switch 440 is operated to its other position, however, the pulse presented to the line 258 is delayed by one pulse time, so that the gate 64 does not become enabled until one pulse time later.

The switch 442 is operative to select a pulse for resetting the RS flip-flop 250. When the switch is in its right-hand position, the resetting of the flip-flop 2S0 occurs at the same time as described above. When the switch 442 is in its middle position, the flip-flop 260is reset one pulse time earlier, and when the switch 442 is in its left-hand position, the flip-flop 250 is reset two pulse times earlier.

By operation of the switches 440 and 442, the starting and ending times of the window pulse are made adjustable, so that notes octavely related to notes immediately above or below the solo note are inhibited as their pulses do not coincide with the window pulse.

FIG. 9 illustrates waveforms of pulses developed at various locations throughout the system during each cycle of operation. The reference numeral accompanying each waveform is the same as that of the line or terminal on which the waveform appears.

It will be appreciated from the foregoing that the present invention is eminently suitable for generating harmony beneath the uppermost solo note played by an operator with the right-hand or solo keyboard. Of course, the present invention may also be employed with an instrument having only a single keyboard, and, in that event, the right-hand portion of the keyboard is regarded as the upper manual and the left-hand portion as the lower manual. The separate voicing of the harmonizing notes c'losely simulates an orchestration effect in which each part of the harmony is played by a separate instrument, so that the effect of a so-called combo or ensemble may be created by an operator of a single instrument. The notes selected by the operator's left hand may be sounded simultaneously with the solo and harmonizing notes, with yet another different voice, or in one of the voices selected for the solo or harmonizing notes. Alternatively, the notes selected by the operator's left hand may be employed only for selection of the harmonizing notes, and not sounded independently. A switch is provided for enabling the operator to select the desired operation of the keys of the lower manual.

The components of the present invention are readily available in the form of integrated circuits, so that construction and assembly of the apparatus is greatly simplified. In addition, only a single switch is required for each key of the keyboard or keyboards, so that physical organization of the components is also simplified.

It will be appreciated that various additions and modifications may be made in the apparatus described herein without departing from the essential features of novelty thereof, which are intended to be defined and secured by the appended claims.

The present invention may be employed with an organ having key switches which close d.c. circuits for operating the keyers, as described herein, or also with organs in which the tones to be sounded are selected in accordance with the time encoded position of pulses of a pulse train, as described in the copending application 17 of Morcz and Moore, Ser. No. 323,245., for Electronic Musical Instrument.

The logic components illustrated and referred to herein are preferably transistor transistor logic (T'TL), made by a variety of manufacturers, such as Texas Instruments Company and others.

What is claimed is:

I. In an electronic musical instrument having a source of tone signals, an output system, and a keyboard with an upper manual portion and a lower manual portion, a system comprising:

a. drive means for producing a plurality of signals for use in scanning the keys of the keyboard,

b. scanning means connected to said drive means for receiving said signalg, and operative to scan the keys of the keyboard for producing first signals in response to operation of the keys of the upper manual and second signals responsive to operation of the keys of the lower manual,

c. means connected with said scanning means and responsive to said first signals and said second signals for producing third signals in accordance with the operated keys of the upper manual and of the lower manual only when keys of boththe upper and lower manuals are simultaneously operated,

d. said third signals comprising a train of pulses encoded in time position in response tooperated keys of both the upper manual and the lower manual, means synchronized with said scanning means and responsive to said third signals for producing a combination of output signals uniquely dependent on the time positions of pulses in said train of pulses, and

. a plurality of keyers responsive to said output signals for keying selected ones of said tone signals to said output system.

2. Apparatus according to claim 1 wherein said scanning means comprises means for selectively energizing a plurality of scanning lines, and means for connecting said scanning lines in circuit individually with key operated switches operating in response to depression of the keys of said upper manual.

3. Apparatus according to claim 1, wherein said scanning means comprises means for selectively energizing a plurality of scanning lines, connecting means for connecting each of said lines in circuit with key operated switches operated in response to depression of octavely related keys of said lower manual, and output means connected in circuit with said connecting means for producing said first signals.

4. Apparatus according to claim 1, including a plurality of latch means connected with said scanning means by said synchronized means which includes means for operating said latch means individually in response to successive ones of the pulses of said pulse train, each of said latch means being adapted to manifest a representation of the time position of the pulse to which it is responsive.

5. Apparatus according to claim 4, wherein each of said latch means includes a first latch adapted to manifest the binary representation corresponding to a note represented by the time position of a separate pulse of said pulse train, and a second latch adapted to manifest the binary representation corresponding to a predetermined group of pulses of said pulse train which contains said separate pulse.

6. Apparatus according to claim 5, including a tone signal generator for generating a plurality of tone signals, each having frequency which is octavely related to tones of the chromatic scale, and signal selector means having a plurality of first input terminals connected to the said tone signal generator and a plurality of control terminals connected to said first latch for selecting one of said plurality of signals in response to the binary representation manifested by said first latch.

7. Apparatus according to claim 6, including a multistage binary counter having its input connected to the output of said signal selector means, and octave selector means having a plurality of input terminals individually connected to each stage of said binary counter and adapted to connect the output of a selected one of said stages to an output terminal in response to the binary representation manifested by said second latch.

8. Apparatus according to claim 7, including a second multi-stage binary counter having its input connected to the output of said octave selector means, and means for connecting the output of each stage of said second binary counter individually with one of a plurality of output terminals.

9. Apparatus according to claim 1, including a plurality of voicing units, means for connecting a separate one of said voicing units with each of a plurality of said keyers, and means for connecting the outputs of said voicing units to the output system of said instrument.

10. In an electronic musical instrument having a source of tone signals, an output system, and a keyboard having a plurality of keys adapted to select certain ones of said tone signals for connection with said output system, a system comprising:

a. drive means for producing a plurality of pulses for use in scanning keys of the keyboard,

b. pulse producing means connected to a first portion of said keyboard and to said drive means and responsiye to depression of the endmost one of the operated keys of one portion of said keyboard means for producing a pulse encoded in time position in accordance with the identity of said end most key, second pulse producing means connected to a second portion of said keyboard and to said drive means and responsive to depression of all of said keys for producing pulses encoded in time position in accordance with the identity of said keys, c. initiating means connected to said pulse producing means and responsive to production of said pulse for initiating a predetermined time interval less than the interval required for a complete scan of said keyboard,

d. selecting means connected to said initiating means and to said second pulse producing means and operative during said predetermined time interval for producing a pulse train composed of a plurality of pulses encoded in time position in accordance with the identity of one or more operated keys of said second portion of said keyboard means, means synchronized with said drive means and responsive to said third signals for producing a combination of output signals uniquely dependent on the time positions of pulses in said train of pulses, and

ev a plurality of keyers responsive to said output signals for selectively connecting selected ones of said tone signals with said output system.

ll. Apparatus according to claim 10, wherein each of said keyers is connected to a tone signal corresponding to a key located within a predetermined number of keys adjacent said endmost key.

l2. Apparatus according to claim 11, including selectively operable switch means connected with said selecting means for selecting said predetennined number of keys.

13. Apparatus according to claim 11, including selectively operable switch means connected with said selecting means for inhibiting the production of pulses within said pulse train which are octavely related with keys located within a second predetermined number of keys adjacent said endmost key.

[4. Apparatus according to claim [0, wherein said endmost key is the most right-hand key of said keyboard means which is depressed.

15. Apparatus according to claim 10, wherein said second portion of said keyboard means comprises that portion of said keyboard means which is customarily played with the left hand of the player-user.

16. Apparatus according to claim 10, wherein said keyboard means comprises a single keyboard.

17. In an electronic musical instrument having a source of tone signals, an output system, and a keyboard having a plurality of keys adapted to select certain ones of said tone signals for connection with said output system, a system comprising:

a. means for generating a plurality of pulses in time sequential fashion,

b. first means connected to said generating means and to said keyboard and responsive to operation of a first group of keys of said keyboard which are customarily played with the right hand of a playeruser,

c. second means connected with said generating means and with said keyboard and responsive to operation of a second group of keys of said key- 20 board which are customarily played with the left hand of a player-user,

d. third means connected with said first and second means and responsive to operation of one of said first group of keys and one of said second group of keys for producing a coded representation of a plurality of tones which correspond to the range of frequencies of tones normally selected by said first group of keys and which correspond to the note names of tones normally selected by said second group of keys, and

E. a fourth means synchronized with said generating means for coupling said coded representation of said plurality of tones to a plurality of keyers for selectively connecting certain ones of said tone signals with said output system.

18. Apparatus according to claim 17, including a plurality of voicing means individually connected to said keyers and to said output system, for sounding each of said plurality of tones in an individual voice.

[9. Apparatus according to claim 17, wherein said third means comprises means for producing said coded representation in response to a predetermined maximum number of depressed keys of said second group of keys.

20. Apparatus according to claim 19, wherein said third means includes means for producing said coded representation in response to the keys of said second group of keys which are depressed, and in accordance with the relation of the depressed key of said second group to the depressed key of said first group representative of the highest pitch of all the depressed keys of said first group.

t t i i 

1. In an electronic musical instrument having a source of tone signals, an output system, and a keyboard with an upper manual portion and a lower manual portion, a system comprising: a. drive means for producing a plurality of signals for use in scanning the keys of the keyboard, b. scanning means connected to said drive means for receiving said signals, and operative to scan the keys of the keyboard for producing first signals in response to operation of the keys of the upper manual and second signals responsive to operation of the keys of the lower manual, c. means connected with said scanning means and responsive to said first signals and said second signals for producing third signals in accordance with the operated keys of the upper manual and of the lower manual only when keys of both the upper and lower manuals are simultaneously operated, d. said third signals comprising a train of pulses encoded in time position in response to operated keys of both the upper manual and the lower manual, means synchronized with said scanning means and responsive to said third signals for producing a combination of output signals uniquely dependent on the time positions of pulses in said train of pulses, and e. a plurality of keyers responsive to said output signals for keying selected ones of said tone signals to said output system.
 2. Apparatus according to claim 1 wherein said scanning means comprises means for selectively energizing a plurality of scanning lines, and means for connecting said scanning lines in circuit individually with key operated switches operating in response to depression of the keys of said upper manual.
 3. Apparatus according to claim 1, wherein said scanning means comprises means for selectively energizing a plurality of scanning lines, connecting means for connecting each of said lines in circuit with key operated switches operated in response to depression of octavely related keys of said lower manual, and output means connected in circuit with said connecting means for producing said first signals.
 4. Apparatus according to claim 1, including a plurality of latch means connected with said scanning means by said synchronized means which includes means for operating said latch means individually in response to successive ones of the pulses of said pulse train, each of said latch means being adapted to manifest a representation of the time position of the pulse to which it is responsive.
 5. Apparatus according to claim 4, wherein each of said latch means includes a first latch adapted to manifest the binary representation corresponding to a note represented by the time position of a separate pulse of said pulse train, and a second latch adapted to manifest the binary representation corresponding to a predetermined group of pulses of said pulse train which contains said separate pulse.
 6. Apparatus according to claim 5, including a tone signal generator for generating a plurality of tone signals, each having frequency which is octavely related to tones of the chromatic scale, and signal selector means having a plurality of first input terminals connected to the said tone signal generator and a plurality of control terminals connected to said first latch for selecting one of said plurality of signals in response to the binary representation manifested by said first latch.
 7. Apparatus according to claim 6, including a multi-stage binary counter having its input connected to the output of said signal selector means, and octave selector means having a plurality of input terminals individually connected to each stage of said binary counter and adapted to connect the output of a selected one of said stages to an output terminal in response to the binary representation manifested by said second latch.
 8. Apparatus according to claim 7, including a second multi-stage binary counter having its input connected to the outpuT of said octave selector means, and means for connecting the output of each stage of said second binary counter individually with one of a plurality of output terminals.
 9. Apparatus according to claim 1, including a plurality of voicing units, means for connecting a separate one of said voicing units with each of a plurality of said keyers, and means for connecting the outputs of said voicing units to the output system of said instrument.
 10. In an electronic musical instrument having a source of tone signals, an output system, and a keyboard having a plurality of keys adapted to select certain ones of said tone signals for connection with said output system, a system comprising: a. drive means for producing a plurality of pulses for use in scanning keys of the keyboard, b. pulse producing means connected to a first portion of said keyboard and to said drive means and responsive to depression of the endmost one of the operated keys of one portion of said keyboard means for producing a pulse encoded in time position in accordance with the identity of said endmost key, second pulse producing means connected to a second portion of said keyboard and to said drive means and responsive to depression of all of said keys for producing pulses encoded in time position in accordance with the identity of said keys, c. initiating means connected to said pulse producing means and responsive to production of said pulse for initiating a predetermined time interval less than the interval required for a complete scan of said keyboard, d. selecting means connected to said initiating means and to said second pulse producing means and operative during said predetermined time interval for producing a pulse train composed of a plurality of pulses encoded in time position in accordance with the identity of one or more operated keys of said second portion of said keyboard means, means synchronized with said drive means and responsive to said third signals for producing a combination of output signals uniquely dependent on the time positions of pulses in said train of pulses, and e. a plurality of keyers responsive to said output signals for selectively connecting selected ones of said tone signals with said output system.
 11. Apparatus according to claim 10, wherein each of said keyers is connected to a tone signal corresponding to a key located within a predetermined number of keys adjacent said endmost key.
 12. Apparatus according to claim 11, including selectively operable switch means connected with said selecting means for selecting said predetermined number of keys.
 13. Apparatus according to claim 11, including selectively operable switch means connected with said selecting means for inhibiting the production of pulses within said pulse train which are octavely related with keys located within a second predetermined number of keys adjacent said endmost key.
 14. Apparatus according to claim 10, wherein said endmost key is the most right-hand key of said keyboard means which is depressed.
 15. Apparatus according to claim 10, wherein said second portion of said keyboard means comprises that portion of said keyboard means which is customarily played with the left hand of the player-user.
 16. Apparatus according to claim 10, wherein said keyboard means comprises a single keyboard.
 17. In an electronic musical instrument having a source of tone signals, an output system, and a keyboard having a plurality of keys adapted to select certain ones of said tone signals for connection with said output system, a system comprising: a. means for generating a plurality of pulses in time sequential fashion, b. first means connected to said generating means and to said keyboard and responsive to operation of a first group of keys of said keyboard which are customarily played with the right hand of a player-user, c. second means connected with said generating means and with said keyboard and responsive to operation of a second group of keys of said keyboard which are customarily played with the left hand of a player-user, d. third means connected with said first and second means and responsive to operation of one of said first group of keys and one of said second group of keys for producing a coded representation of a plurality of tones which correspond to the range of frequencies of tones normally selected by said first group of keys and which correspond to the note names of tones normally selected by said second group of keys, and E. a fourth means synchronized with said generating means for coupling said coded representation of said plurality of tones to a plurality of keyers for selectively connecting certain ones of said tone signals with said output system.
 18. Apparatus according to claim 17, including a plurality of voicing means individually connected to said keyers and to said output system, for sounding each of said plurality of tones in an individual voice.
 19. Apparatus according to claim 17, wherein said third means comprises means for producing said coded representation in response to a predetermined maximum number of depressed keys of said second group of keys.
 20. Apparatus according to claim 19, wherein said third means includes means for producing said coded representation in response to the keys of said second group of keys which are depressed, and in accordance with the relation of the depressed key of said second group to the depressed key of said first group representative of the highest pitch of all the depressed keys of said first group. 